Well, you have to consider that they have wings. Any creature with wings gives up a certain measure of maneuverability on the ground. Depending on the type of wings, they’re going to be more vulnerable there. Think about it like attaching a fairly heavy contraption to both your shoulder blades that’s also pretty delicate. Organic wings with hollow bones are very fragile.
If we’re talking about Archangel from X-men, who has had his wings ripped out and replaced with metal ones then it’s a different story.
So, depending on the rules you’ve decided to use in your story, it could be fairly maneuverable to ground equals death. Or, at least, no flying for six months if ever. They’d be giving up a lot of their maneuverability on the ground as the wings will get in the way even when folded. There’s also the extra weight to account for which will unbalance them. It’s important to remember that the martial combat techniques we have are designed for humans and human bodies. This doesn’t mean they couldn’t be modified for someone with a different body type or concerns, but adding wings will throw off the body’s equilibrium. In nature, some creatures have wings for a reason and their behavior is built around that. They trade aerial movement for the ability to move well on the ground. The wings are going to get in the way when you’re fighting, especially if you’re trying to use any sort of human combat techniques. This is because combat actually relies more heavily on power or force generated through momentum than it does strength.
You need rotation, balance, and the ability to turn the body. If the elbow is getting caught in the wings, or the extra weight tips them when they pull their arm back, turn their hips, or what have you then it could be very dangerous.
The only thing I can think of the wings being helpful for is sending multiple enemies stumbling back when they open or buffeting.
The character could fight on the ground if they really want to, but it won’t be the place where they have the advantage.